In some situations, the nerve becomes infected in the tooth, even though there appears to be no apparent reason. Many of these teeth have no pain, but an abscess may appear in the gum tissue (as seen in this example), or may be detected on an x-ray. Even though there may be no discomfort, treatment of these situations is required to prevent the infection from destroying bone and tissue, and also to help prevent loss of the tooth.
When the nerve becomes infected in a tooth, there is bacteria and debris that build up within the canal of the root. Over time, this debris can cause the tooth to discolor. Although many of these teeth have no pain, when a tooth starts to appear dark, it may indicate that a root canal is required.
Regular checkups and x-rays are important in detecting these types of infections.